Micropatterned PDMS Damping Layer Integration to Enhance the Fidelity of Piezoelectric MEMS Speakers Without SPL Penalty

This study proposes a novel integration of a micropatterned PDMS film for passive vibration damping in piezoelectric MEMS speakers. This approach addresses the challenges of on-wafer PDMS micropatterning while maintaining compatibility with MEMS wafer fabrication processes. Compared to conventional designs, this approach has been demonstrated to reduce the Q-factor by up to 75% under vacuum conditions and 45% under atmospheric conditions. The enhanced damping enables effective harmonic attenuation, lowering the peak total harmonic distortion (THD) to 78% and 72% of the values observed in the conventional drum and cantilever speakers without PDMS, respectively, while maintaining consistent sound pressure levels (SPLs). These results provide a scalable solution for improving piezoelectric MEMS speaker performance, with applicability to in-ear devices.